Abstract: Immersion tin-lead baths are provided, preferably free of hypophosphite ion, comprising a strongly acidic aqueous solution comprised of thiourea, water-soluble sources of divalent tin and lead, a weak acid, and a weak base.

Abstract: For attaining adhesion between copper circuitry innerlayers and pre-preg layers in a multilayer printed circuit, a conversion coating of copper oxide is provided on the metallic copper surfaces in a manner which develops an altered topography of the underlying metallic copper surfaces. Thereafter, a controlled dissolution and removal of a substantial amount of the copper oxide is effected, in a manner which does not adversely affect the already-developed topography of the underlying metallic copper, and such that the innerlayer, at the time of assembly with the pre-preg layers, has copper surfaces consisting of the topographically altered metallic copper and a relatively small amount of copper oxide thereon. Excellent bonding strengths are achieved with decreased incidence of pink ring formation as compared to conventional processes utilizing copper oxide for adhesion promotion.

Abstract: For attaining adhesion between copper circuitry innerlayers and pre-preg layers in a multilayer printed circuit, a conversion coating of copper oxide is provided on the metallic copper surfaces in a manner which develops an altered topography of the underlying metallic copper surfaces. Thereafter, a controlled dissolution and removal of a substantial amount of the copper oxide is effected, in a manner which does not adversely affect the already-developed topography of the underlying metallic copper, and such that the innerlayer, at the time of assembly with the pre-preg layers, has copper surfaces consisting of the topographically altered metallic copper and a relatively small amount of copper oxide thereon. Excellent bonding strengths are achieved with decreased incidence of pink ring formation as compared to conventional processes utilizing copper oxide for adhesion promotion.

Abstract: Metallic surfaces to be provided with a tin-lead coating from an immersion tin-lead bath, and particularly copper surfaces (e.g., through-holes, pads) of a printed circuit board having other metallic surfaces thereon covered by a hydrophobic solder mask, are prepared for receipt of immersion tin-lead coating by, e.g., contact thereof with a strongly acidic aqueous pre-dip solution containing at least one surface active agent functional to reduce the surface tension of the pre-dip solution and/or to provide the solution with improved affinity for the metallic surface.

Abstract: Non-conductive surfaces, particularly through-hole surfaces in double-sided or multi-layer printed circuit board, are treated (conditioned) to receive void-free, adherent electroless metal coatings by contact of the surfaces with an organosilane preparatory to catalyzation and metallization.

Abstract: A process for selective metallization of a substrate in a predetermined desired pattern, and particularly for the manufacture of printed circuit boards, in which a substrate patterned in desired manner with resist material is treated with conditioning agent, adjuvant and deactivating agent preparatory to catalytic activation and electroless deposit of metal flash. By proceeding in this manner, adherent flash metal deposit is achieved on non-resist areas without encountering significant plating on resist areas. Following metal flash deposit, the resist can be easily and cleanly stripped and additional metal then built up on the flash metal.

Abstract: Shielding means for electromagnetic radiation, particularly that of radio frequency, comprises a enclosure fabricated from non-conductive material and having on at least one of the interior or exterior walls a layer of copper metal. The latter has been applied by coating the surface of the wall with a suspension of particles of cuprous oxide (or like non-conductive metal derivatives capable of being reduced to conductive free metal) in a curable resinous material, at least partially curing the coating, reducing to free metal the cuprous oxide or like particles in the surface of the coating and then electrolessly plating the coating with copper.

Abstract: An additive process for making printed circuit boards utilizing aqueous alkaline strippable resists, in which a suitable insulating substrate is patterned with the resist, the resist-patterned substrate catalyzed to electroless metal deposition, the resist then stripped completely from the substrate, utilizing an aqueous alkaline solution, preferably containing a reducing agent, and the electroless metal then deposited over the areas of the substrate catalyzed in the desired pattern.

Abstract: Multilayer printed circuit boards are fabricated by preparing a first layer in conventional manner by forming a resist image on a copper clad substrate, etching away unwanted copper, removing the resist from the circuit pattern and optionally applying a dielectric mask such as conventional solder mask to selected portions of the circuit pattern. A second layer, and optionally one or more subsequent layers, are fabricated by providing an image of a second circuit pattern in a predetermined location on said first layer, the image being formed using a suspension of cuprous oxide in a curable resin material. The image is cured at least partially and subjected to chemical reduction to convert at least a portion of the cuprous oxide to metallic copper such that the unreduced cuprous oxide in resin serves as a dielectric layer.

Abstract: A process for selective metallization of a substrate in a predetermined desired pattern, and particularly for the manufacture of printed circuit boards, in which a substrate patterned in desired manner with resist material is treated with conditioning agent, adjuvant and deactivating agent preparatory to catalytic activation and electroless deposit of metal flash. By proceeding in this manner, adherent flash metal deposit is achieved on non-resist areas without encountering significant plating on resist areas. Following metal flash deposit, the resist can be easily and cleanly stripped and additional metal then built up on the flash metal.

Abstract: Suitably complexed cupric solutions can deposit conductive copper films electrolessly on properly catalyzed non-conductive substrates, at plating bath pH values in the range of about 2.0 to 3.5, using a non-formaldehyde reducer such as hypophosphite. Certain conditions are critical to successful results: (1) ability of the complexer selected to chelate copper at pH values of 2.0 to 3.5 at elevated temperatures (140.degree. to 160.degree. F.); (2) avoidance of certain anions, such as halides and acetates, in significant concentrations in the plating solution; and (3) provision of an "active" catalytic surface on the non-conductive substrate.

Abstract: Electroless copper deposition solutions, and method of electrolessly depositing copper onto a workpiece using these solutions, are disclosed. The solutions contain, in addition to water as the usual solvent, a soluble source of copper ions, a complexing agent or mixture of agents to maintain the copper in solution, and a copper reducing agent effective to reduce the copper ions to metallic copper as a deposit or plating on a prepared surface of a workpiece brought into contact with the solution.

Abstract: Electroless copper deposition solutions, and method of electrolessly depositing copper onto a workpiece using these solutions, are disclosed. The solutions contain, in addition to water as the usual solvent, a soluble source of copper ions, a complexing agent or mixture of agents to maintain the copper in solution, and a copper reducing agent effective to reduce the copper ions to metallic copper as a deposit or plating on a prepared surface of a workpiece brought into contact with the solution.